Derivation of the predicted no-effect concentration for organophosphate esters and the associated ecological risk in surface water in China

Organophosphate esters (OPEs), as re-emerging contaminants considered to be a potential health concern, are ubiquitous in the environment and have been widely investigated. However, little is known on the safe OPE concentrations in the water quality criteria for the protection of the aquatic environment, which is an indispensable part of environmental management. In the present study, aquatic acute and chronic predicted no-effect concentrations (PNECs) of six frequently detected OPEs were derived from the hazardous concentrations for 5% of species (HC₅s), respectively. The acute PNECs for the selected OPEs ranged from 17.70 to 3562 μg/L, while the chronic PNECs ranged from 4.6 × 10⁻⁴ to 61.85 μg/L. Among these OPEs, tricresyl phosphate (TCrP) exhibited the lowest acute PNEC, while tris(1,3-dichloro-2-propyl) phosphate (TDCPP) presented chronic PNEC, which indicated that it has a higher toxicity effect on the aquatic environment. Furthermore, the aquatic ecological risks of individual OPEs (except for TDCPP) were deemed to be relatively low in Chinese surface water; however, the aquatic ecological risks of TDCPP and ΣOPEs indicated that they have potential adverse effects and should be considered as a potential health concern. The probability of 5% of aquatic organisms being affected by ΣOPEs was in the range of 0.21 to 17.39% based on the joint probability curve method.